1. Field of the Invention
The present invention relates to a process for the manufacture of identification elements by recording a hologram of an object carrying information on a light-sensitive recording material with the aid of an object beam and a reference beam; further, the present invention relates to an apparatus for performing the process.
The invention is used for the production of identity documents, such as identity cards, check cards, credit cards, customer's cards and other identification elements which serve to identify their bearer.
2. Description of the Prior Art
According to a known system, a hologram is disposed in or on an identification element, such as an identity or other card. The hologram contains, in code form, information which can be read only under special optical conditions. This information is recorded by forming a hologram on a suitable recording material, using, as the object, the card with printing and personal data thereon. The hologram is made separately and only then combined with the card, for example by inserting the recording material carrying the hologram in an aperture in the card. Alternatively, the recording material carrying the hologram may be attached to the back of the card.
This means that the hologram is produced on the recording material by means of laser light, only after the individual data were written on the card and while the recording material is separated from the card. Then the card and the hologram belonging to it are affixed, i.e. the individual cards are brought together with their holograms and united. This method does not absolutely exclude the possibility of the holograms being assigned to a wrong card during subsequent insertion in or combination with the card, so that continuous thorough checking is necessary.
Since each hologram is combined with the appropriate card in a conveyor-line operation, a number of holograms being continuously combined with the same number of cards, it is obvious that, if the series of holograms is displaced for example by a single hologram only from the series of cards, all identification elements become useless because each hologram is assigned to the wrong card.
As a further problem of the known process, it is difficult to insert the hologram into the aperture of the card without distorting or displacing it. A perfect insertion of the hologram is required, however, because when the identification element is placed in a reader for reconstruction of the hologram, the reconstructed image otherwise would partially or wholly leave the area of the screen.
The identification elements frequently are composed of several layers, for example of the core of the card which carries the information and two protective films which are laminated to both surfaces of the core to protect it against mechanical abrasion and tampering by unauthorized persons. Lamination is normally performed by heat-sealing the films under pressure and at elevated temperatures, so that thermoplastic materials, e.g. polyvinyl chloride, are preferred as materials for the identification elements and the protective film.
Manufacturers and users of identity documents, e.g. identity cards, check cards, credit cards, customer's cards and the like, are constantly demanding better safety from falsification and unauthorized use, especially of identification elements used for credit transactions. On the other hand, expenditures for safety controls should be low in order to promote a wide use of such identification elements.